Behavioral and Neural Dynamics of Interpersonal Synchrony Between Performing Musicians: A Wireless EEG Hyperscanning Study

Interpersonal synchrony refers to the temporal coordination of actions between individuals and is a common feature of social behaviors, from team sport to ensemble music performance. Interpersonal synchrony of many rhythmic (periodic) behaviors displays dynamics of coupled biological oscillators. The current study addresses oscillatory dynamics on the levels of brain and behavior between music duet partners performing at spontaneous (uncued) rates. Wireless EEG was measured from N = 20 pairs of pianists as they performed a melody first in Solo performance (at their spontaneous rate of performance), and then in Duet performances at each partner’s spontaneous rate. Influences of partners’ spontaneous rates on interpersonal synchrony were assessed by correlating differences in partners’ spontaneous rates of Solo performance with Duet tone onset asynchronies. Coupling between partners’ neural oscillations was assessed by correlating amplitude envelope fluctuations of cortical oscillations at the Duet performance frequency between observed partners and between surrogate (re-paired) partners, who performed the same melody but at different times. Duet synchronization was influenced by partners’ spontaneous rates in Solo performance. The size and direction of the difference in partners’ spontaneous rates were mirrored in the size and direction of the Duet asynchronies. Moreover, observed Duet partners showed greater inter-brain correlations of oscillatory amplitude fluctuations than did surrogate partners, suggesting that performing in synchrony with a musical partner is reflected in coupled cortical dynamics at the performance frequency. The current study provides evidence that dynamics of oscillator coupling are reflected in both behavioral and neural measures of temporal coordination during musical joint action.

Electrophysiology of hiPSC-Cardiomyocytes Co-Cultured with HEK Cells Expressing the Inward Rectifier Channel

The immature electrophysiology of human-induced pluripotent stem cell-derived cardiomyocytes (hiCMs) complicates their use for therapeutic and pharmacological purposes. An insufficient inward rectifying current (IK1) and the presence of a funny current (if) cause spontaneous electrical activity. This study tests the hypothesis that the co-culturing of hiCMs with a human embryonic kidney (HEK) cell-line expressing the Kir2.1 channel (HEK-IK1) can generate an electrical syncytium with an adult-like cardiac electrophysiology. The mechanical activity of co-cultures using different HEK-IK1:hiCM ratios was compared with co-cultures using wildtype (HEK–WT:hiCM) or hiCM alone on days 3–8 after plating. Only ratios of 1:3 and 1:1 showed a significant reduction in spontaneous rate at days 4 and 6, suggesting that IK1 was influencing the electrophysiology. Detailed analysis at day 4 revealed an increased incidence of quiescent wells or sub-areas. Electrical activity showed a decreased action potential duration (APD) at 20% and 50%, but not at 90%, alongside a reduced amplitude of the aggregate AP signal. A computational model of the 1:1 co-culture replicates the electrophysiological effects of HEK–WT. The addition of the IK1 conductance reduced the spontaneous rate and APD20, 50 and 90, and minor variation in the intercellular conductance caused quiescence. In conclusion, a 1:1 co-culture HEK-IK1:hiCM caused changes in electrophysiology and spontaneous activity consistent with the integration of IK1 into the electrical syncytium. However, the additional electrical effects of the HEK cell at 1:1 increased the possibility of electrical quiescence before sufficient IK1 was integrated into the syncytium.

Spontaneous Production Rates in Music and Speech

Individuals typically produce auditory sequences, such as speech or music, at a consistent spontaneous rate or tempo. We addressed whether spontaneous rates would show patterns of convergence across the domains of music and language production when the same participants spoke sentences and performed melodic phrases on a piano. Although timing plays a critical role in both domains, different communicative and motor constraints apply in each case and so it is not clear whether music and speech would display similar timing mechanisms. We report the results of two experiments in which adult participants produced sequences from memory at a comfortable spontaneous (uncued) rate. In Experiment 1, monolingual pianists in Buffalo, New York engaged in three production tasks: speaking sentences from memory, performing short melodies from memory, and tapping isochronously. In Experiment 2, English-French bilingual pianists in Montréal, Canada produced melodies on a piano as in Experiment 1, and spoke short rhythmically-structured phrases repeatedly. Both experiments led to the same pattern of results. Participants exhibited consistent spontaneous rates within each task. People who produced one spoken phrase rapidly were likely to produce another spoken phrase rapidly. This consistency across stimuli was also found for performance of different musical melodies. In general, spontaneous rates across speech and music tasks were not correlated, whereas rates of tapping and music were correlated. Speech rates (for syllables) were faster than music rates (for tones) and speech showed a smaller range of spontaneous rates across individuals than did music or tapping rates. Taken together, these results suggest that spontaneous rate reflects cumulative influences of endogenous rhythms (in consistent self-generated rates within domain), peripheral motor constraints (in finger movements across tapping and music), and communicative goals based on the cultural transmission of auditory information (slower rates for to-be-synchronized music than for speech).

Studying the history of synthesis and chemical structure of pyrethrins and synthetic pyrethroids, and mutagenicity of pyrethroids in the in vivo test for micronucleus induction (literature review and data of own studies)

Introduction. Pyrethroids are analogues of natural pyrethrins, primarily isolated from plants of the genus Pymthrum, a family of Asteraceae known for their insecticidal properties. Objective. To study literature data on the history of synthesis, peculiarities of the chemical structure of pyrethrins, pyrethroids and their most common isomers, a combination of synthetic pyrethroids (SPs) with other chemical substances and insecticidal activity of SPs. Also, to perform an experimental assessment of SP mutagenicity. Materials and Мethods. For the literature review, data of international organizations, electronic databases and articles of the authors from different countries were used. To study SP mutagenicity, in vivo test for micronucleus (MN) induction in polychromatophilic erythrocytes (PCE) in mice bone marrow was used. Five active substances of SPs were studied: Cypermethrin 94.0 % at the doses of 46.0, 9.2,1.84 mg/kg body weight, 2 samples of Alpha-cypermethrin — 94.0 and 94.7 % at the doses of 20.0,2.0, 0.2 mg/kg, and 2 samples of Lambda-cyhalothrin — 95.2 and 97.1 % at the doses of 5.0,1.0, 0.2 mg/kg. Results and Discussion. The history of SP synthesis dates back about 70 years. Currently, a significant number of SPs were synthesised that differ in chemical structure, have different strength of insecticidal action, as well as may be used in combination with other compounds. Results of experimental studies suggest that Cypermethrin at the doses from 46.0 to 1.84 mg/kg body weight, 2 samples of Alpha-cypermethrin at the doses from 20.0 to 0.2 mg/kg body weight, as well as 2 samples of Lambda-cyhalothrin at the doses 1.0 and 0.2 mg/kg did not show significant increase in MNPCE level in PCs. However, both samples of Lambda-cyhalothrin at the doses: 5.0 mg/kg body weight induced statistically significant exceeding of the spontaneous rate of MNPCE (р < 0.05). Conclusion. Cypermethrin at the doses from 46.0 to 1.84 mg/kg body weight did not show a significant increase in MNPCE level. Samples of Alpha-cypermethrin at the doses from 20.0 to 0.2 mg/kg body weight did not show a significant increase in MN level. Samples of Lambda-cyhalothrin at the doses from 1.0 to 0.2 mg/kg did not show a significant increase in MN level. Samples of Lambda-cyhalothrin at the doses: 5.0 mg/kg body weight induced statistically significant exceeding of the spontaneous rate of MNPCE in comparison with the data of negative and historical controls.

Musicians’ Natural Frequencies of Performance Display Optimal Temporal Stability

Many human action sequences, such as speaking and performing music, are inherently rhythmic: Sequence events are produced at quasi-regular temporal intervals. A wide range of interindividual variation has been noted in spontaneous production rates of these rhythmic action sequences. Dynamical theories of motor coordination suggest that individuals spontaneously produce rhythmic sequences at a natural frequency characterized by minimal energy expenditure and maximal temporal stability, relative to other frequencies. We tested this hypothesis by comparing the temporal variability with which musicians performed rhythmic melodies at their natural spontaneous rate with variability in their performances at faster and slower rates. Musicians’ temporal variability was lowest during performances at their spontaneous rate; in addition, performers’ tempo drift during trials at other rates showed bias toward their spontaneous rate. This study provides the first direct evidence that spontaneous rates of motor coordination represent optimally stable natural frequencies of endogenous rhythms.